diff --git a/Assets/Mirror/Components/Discovery/NetworkDiscoveryBase.cs b/Assets/Mirror/Components/Discovery/NetworkDiscoveryBase.cs
index 8e13f01d0..441734402 100644
--- a/Assets/Mirror/Components/Discovery/NetworkDiscoveryBase.cs
+++ b/Assets/Mirror/Components/Discovery/NetworkDiscoveryBase.cs
@@ -85,9 +85,10 @@ public virtual void Start()
                 transport = Transport.active;
 
             // Server mode? then start advertising
-#if UNITY_SERVER
-            AdvertiseServer();
-#endif
+            if (Utils.IsHeadless())
+            {
+                AdvertiseServer();
+            }
         }
 
         public static long RandomLong()
diff --git a/Assets/Mirror/Components/NetworkRoomManager.cs b/Assets/Mirror/Components/NetworkRoomManager.cs
index e210e730f..11f771431 100644
--- a/Assets/Mirror/Components/NetworkRoomManager.cs
+++ b/Assets/Mirror/Components/NetworkRoomManager.cs
@@ -251,10 +251,11 @@ public override void OnServerDisconnect(NetworkConnectionToClient conn)
             OnRoomServerDisconnect(conn);
             base.OnServerDisconnect(conn);
 
-#if UNITY_SERVER
-            if (numPlayers < 1)
-                StopServer();
-#endif
+            if (Utils.IsHeadless())
+            {
+                if (numPlayers < 1)
+                    StopServer();
+            }
         }
 
         // Sequential index used in round-robin deployment of players into instances and score positioning
diff --git a/Assets/Mirror/Core/NetworkManager.cs b/Assets/Mirror/Core/NetworkManager.cs
index 05c1813fe..22ae8cff1 100644
--- a/Assets/Mirror/Core/NetworkManager.cs
+++ b/Assets/Mirror/Core/NetworkManager.cs
@@ -221,11 +221,10 @@ public virtual void Start()
             //
             // (tick rate is applied in StartServer!)
             //
-#if UNITY_SERVER
             // don't auto start in editor where we have a UI, only in builds.
             // otherwise if we switch to 'Dedicated Server' target and press
             // Play, it would auto start the server every time.
-            if (!Application.isEditor)
+            if (Utils.IsHeadless() && !Application.isEditor)
             {
                 if (autoStartServerBuild)
                 {
@@ -237,7 +236,6 @@ public virtual void Start()
                     StartClient();
                 }
             }
-#endif
         }
 
         // make sure to call base.Update() when overwriting
@@ -686,10 +684,11 @@ public virtual void OnApplicationQuit()
         // useful for headless benchmark clients.
         public virtual void ConfigureHeadlessFrameRate()
         {
-#if UNITY_SERVER
-            Application.targetFrameRate = sendRate;
-            // Debug.Log($"Server Tick Rate set to {Application.targetFrameRate} Hz.");
-#endif
+            if (Utils.IsHeadless())
+            {
+                Application.targetFrameRate = sendRate;
+                // Debug.Log($"Server Tick Rate set to {Application.targetFrameRate} Hz.");
+            }
         }
 
         bool InitializeSingleton()
diff --git a/Assets/Mirror/Core/NetworkServer.cs b/Assets/Mirror/Core/NetworkServer.cs
index 9b57b28c1..067cde9d1 100644
--- a/Assets/Mirror/Core/NetworkServer.cs
+++ b/Assets/Mirror/Core/NetworkServer.cs
@@ -120,13 +120,16 @@ public static void Listen(int maxConns)
 
                 if (Transport.active is PortTransport portTransport)
                 {
-#if UNITY_SERVER && !UNITY_EDITOR
-                    Console.ForegroundColor = ConsoleColor.Green;
-                    Console.WriteLine($"Server listening on port {portTransport.Port}");
-                    Console.ResetColor();
+                    if (Utils.IsHeadless())
+                    {
+#if !UNITY_EDITOR
+                        Console.ForegroundColor = ConsoleColor.Green;
+                        Console.WriteLine($"Server listening on port {portTransport.Port}");
+                        Console.ResetColor();
 #else
-                    Debug.Log($"Server listening on port {portTransport.Port}");
+                        Debug.Log($"Server listening on port {portTransport.Port}");
 #endif
+                    }
                 }
                 else
                     Debug.Log("Server started listening");
diff --git a/Assets/Mirror/Core/Tools/Utils.cs b/Assets/Mirror/Core/Tools/Utils.cs
index 2ed8dffd0..0c44eb014 100644
--- a/Assets/Mirror/Core/Tools/Utils.cs
+++ b/Assets/Mirror/Core/Tools/Utils.cs
@@ -2,6 +2,7 @@
 using System.Runtime.CompilerServices;
 using System.Security.Cryptography;
 using UnityEngine;
+using UnityEngine.Rendering;
 using UnityEngine.SceneManagement;
 
 namespace Mirror
@@ -32,6 +33,15 @@ public static class Channels
 
     public static class Utils
     {
+        // detect headless / dedicated server mode
+        // in Unity 2019/2020, we need to check if there is no graphics device.
+        // in Unity 2021+, we could check for the #if UNITY_SERVER define.
+        // checking graphics device is safest.
+        // => it works on all Unity versions.
+        // => it keeps all the code active instead of ifdefing it out.
+        public static bool IsHeadless() =>
+            SystemInfo.graphicsDeviceType == GraphicsDeviceType.Null;
+
         public static uint GetTrueRandomUInt()
         {
             // use Crypto RNG to avoid having time based duplicates
diff --git a/Assets/Mirror/Examples/Room/Scripts/NetworkRoomManagerExt.cs b/Assets/Mirror/Examples/Room/Scripts/NetworkRoomManagerExt.cs
index 29f1ccbf6..069913dfb 100644
--- a/Assets/Mirror/Examples/Room/Scripts/NetworkRoomManagerExt.cs
+++ b/Assets/Mirror/Examples/Room/Scripts/NetworkRoomManagerExt.cs
@@ -76,11 +76,14 @@ Setting showStartButton false when the button is pressed hides it in the game sc
         public override void OnRoomServerPlayersReady()
         {
             // calling the base method calls ServerChangeScene as soon as all players are in Ready state.
-#if UNITY_SERVER
-            base.OnRoomServerPlayersReady();
-#else
-            showStartButton = true;
-#endif
+            if (Utils.IsHeadless())
+            {
+                base.OnRoomServerPlayersReady();
+            }
+            else
+            {
+                showStartButton = true;
+            }
         }
 
         public override void OnGUI()
diff --git a/Assets/Mirror/Transports/Multiplex/MultiplexTransport.cs b/Assets/Mirror/Transports/Multiplex/MultiplexTransport.cs
index e85ee809c..fbd2abf61 100644
--- a/Assets/Mirror/Transports/Multiplex/MultiplexTransport.cs
+++ b/Assets/Mirror/Transports/Multiplex/MultiplexTransport.cs
@@ -285,13 +285,16 @@ public override void ServerStart()
 
                 if (transport is PortTransport portTransport)
                 {
-#if UNITY_SERVER
-                Console.ForegroundColor = ConsoleColor.Green;
-                Console.WriteLine($"Server listening on port {portTransport.Port}");
-                Console.ResetColor();
-#else
-                    Debug.Log($"Server listening on port {portTransport.Port}");
-#endif
+                    if (Utils.IsHeadless())
+                    {
+                        Console.ForegroundColor = ConsoleColor.Green;
+                        Console.WriteLine($"Server listening on port {portTransport.Port}");
+                        Console.ResetColor();
+                    }
+                    else
+                    {
+                        Debug.Log($"Server listening on port {portTransport.Port}");
+                    }
                 }
             }
         }